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We assessed the response of Quercus ilex subsp. ballota to the severe summer drought recorded in 1994 in NE Spain through the study of changes in radial growth and wood anatomy. We selected a coppice stand in the Iberian Peninsula, which is characterized by a Mediterranean climate under continental influence. We measured internode length, tree-ring width, mean and maximum vessel diameter, and vessel...
Unique Dracaena cinnabari woodlands on Socotra Islandrelics of the Mio-Pliocene xerophile-sclerophyllous southern Tethys Florawere examined in detail, especially with regard to their age structure. Detailed statistical analyses of sets of 50 trees at four localities were performed in order to define a model reflecting relationships between specific growth habit and actual age. The problematic nature...
This paper explores the temporal stability of growth/climate relationships in ring-width chronologies of Norway spruce [ Picea abies (L.) Karst] and silver fir ( Abies alba Mill) in the Lower Bavarian Forest region in southern Germany. These chronologies were compiled, using both historic and living tree-ring data, with the main aim of developing a dendroclimatic reconstruction for the region covering...
Plant growth and adaptation to cold and freezing temperatures in a CO2-enriched atmosphere have received little attention despite the predicted effects of elevated CO2 on plant distribution and productivity. Norway spruce [Picea abies (L.) Karst.] seedlings from latitudinally distinct seed sources (66N and 60N) were grown for one simulated growth season under controlled conditions in an atmosphere...
The present study was conducted in order to examine the physiological role of free polyamines in flower bud abscission. For this reason five 15-year old pistachio trees cv. Pontikis were selected and half of the main branches were manually defruited in early May. Polyamines were analyzed in three different organs (shoots, leaves and flower buds) from both fruiting and non-fruiting branches, during...
The anatomical defense responses in stems of Norway spruce (Picea abies) clones of different resistance to pathogenic fungi were characterized over time and distance from small mechanical wounds or wounds inoculated with the root rot fungus Heterobasidion annosum. Common responses for both treatments included division of ray parenchyma and other cells in the cambial zone, accumulation of phenolic...
A 15N-tracer experiment was carried out in a stand of adult spruce trees [Picea abies (L.) Karst.] located on the Swiss Plateau in order to investigate the effects of wood ash treatment on seasonal nitrogen fluctuations in fine roots and needles. Treatments included irrigation (W), liquid fertilization (LF) and wood ash (A) application. 15N fluctuation in fine roots and current to 3-year-old needles...
Larch heartwood is appreciated for its good mechanical properties, its colour and its texture, and it is often used outdoors because of its natural durability (decay resistance). In this study the colour of larch heartwood was studied in relation to extractives and decay resistance, with the aim to estimate durability of larch heartwood from its colour. On a total of 293 trees colour in the CIE L*a*b*...
Black spruce [ Picea mariana (Mill.) B.S.P.] and tamarack [ Larix laricina (Du Roi) K. Koch] are the predominant tree species in boreal peatlands. The effects of 34 days of flooding on morphological and physiological responses were investigated in the greenhouse for black spruce and tamarack seedlings in their second growing season (18 months old). Flooding resulted in reduced root hydraulic conductance,...
Water use, drought response and growth were examined under controlled conditions in four interbreeding willow species from different geographical origins (two clones of Salix viminalis L., one clone of S. viminalis S. schwerenii E. Wolf and one clone of S. purpurea L.). The levels of soil water depletion that plants could sustain without wilting varied markedly between the clones. The level of drought...
Little is known about the responses of large, old trees to release from competition, though such trees are of great interest in forest ecology, conservation and silviculture. Increment cores were taken from mature eastern white pines (Pinus strobus L.) in 144 sample points in 12 partially harvested and 6 unharvested control stands in Ontario, Canada, to determine how these trees responded to a structural...
Water-use strategies of Populus tremula and Tilia cordata, and the role of abscisic acid in these strategies, were analysed. P. tremula dominated in the overstorey and T. cordata in the lower layer of the tree canopy of the temperate deciduous forest canopy. Shoot water potential (), bulk-leaf abscisic acid concentration ([ABA]leaf), abscisic acid concentration in xylem sap ([ABA]xyl), and rate of...
Rooting capacity of microshoots derived from a mature clone of Acacia mangium Willd. and from its juvenile progeny was compared in different in vitro conditions and in relation to leaf morphology as a phase change marker. Rooting capacity of the mature clone appeared to depend a lot on rooting medium composition, in contrast to the juvenile plant material. On a SH/3 derived medium with 4M IAA, the...
The natural occurrence of oil glands in various organs such as bark and leaves is well established as a characteristic of Eucalyptus, but this is the first reported case of traumatic oil glands induced in response to wounding. The new phloem enveloping the wound, which had developed within the 2years following branch pruning in 5-year-old Eucalyptus globulus Labill., was morphologically distinct from...
Trees are an integral part of human life, and a vital component of biodiversity. Forest trees in particular are renewable sources of food, fodder, fuel wood, timber and other valuable non-timber products. Due to the rapid growth of population and the human desire to progress, there has been a tremendous reduction in forest cover from the earths surface. To maintain and sustain forest vegetation, conventional...
A miniaturized, porometer-compatible cuvette for measurements of CO2 efflux from woody plant parts at controlled temperature conditions is described. A copper cuvette equipped with a PID-controlled Peltier element regulates cortex temperature in three modes: (1) synchronized with ambient air temperature; (2) at a constant difference in the range of 10C from air temperature; and (3) constant at a temperature...
Analyses of birch leaves (Betula pendula Roth) sampled from trees in the air polluted Krusne hory mountains and Decin sandstone highlands were performed in 1995 and 1998. The results revealed a connection between reduction of air pollutants and overall decrease in sulphur and nitrogen content of the leaves. Simultaneously, in many stands an increase in calcium content and a decrease in contents of...
The development of vascular features in stems of Populus x euramericana was studied in two adjacent floodplain forest stands near the Danube in Austria. The construction of a hydropower plant caused one of the stands to loose contact with the groundwater at the age of 12years, whereas the other stand remained uninfluenced. The investigation estimated the extent of vascular acclimation to altered site...
Patterns in branch permeability with crown depth and permeability at the top of the main stem were analyzed for loblolly pine (Pinus taeda L.) trees from families selected on the basis of growth rate (fast, slow) and crown size (large, small). Analysis of variance with levels of crown size nested within levels of growth rate was used to test for differences in main stem permeability. Permeability...
We investigated the effect of (a) different local climate and (b) thinning of the forest canopy on growth and N status of naturally regenerated European beech seedlings in a beech forest on shallow rendzina soil in southern Germany. For this purpose, a 15N-tracing experiment was conducted during the growing season of the year 2000 with beech seedlings growing on a warm, dry SW-exposed site and a cooler,...
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